Nitric Oxide (NO) is a biosignalling molecule with diverse functions and immense significance to mammalian systems. This grant application seeks partial support for the "Fourth International Meeting on the Biology of Nitric Oxide", to be held September 17-21,1995, on Amelia Island, Florida. By mutual consent, an international meeting on nitric oxide (NO) biology has convened every 2 years, beginning in 1989. The upcoming meeting will be the first of this lineage to be held in the U.S.A. The original 1989 meeting came on the heels of historic discoveries of NO as a product of mammalian cell metabolism and identification of NO as the endothelium- derived relaxing factor and cytostatic factor derived from immunostimulant-activated macrophages. The 1989 meeting served to spawn the field of NO biology by assembling, for the first time, researchers who were working on diverse aspects of what we now appreciate as a common ground. Presently, NO is known to play essential roles in the regulation of vascular tone and blood pressure, maintaining vascular patency, neurosignalling, host-defense, and immune and endocrine cell coordination. Excessive NO synthesis has been implicated in many pathophysiological conditions, including lethal and debilitating diseases of man: vascular shock, stroke, diabetes, neurodegeneration, arthritis and chronic inflammation. Despite its critical roles in physiology and pathophysiology, mammalian cell-derived NO had gone undiscovered until 1987. The international meetings on NO biology have been key to the rapid maturation of our knowledge by facilitating global scientific liaisons and state-of-the-art information exchange. In keeping with prior meetings, communications will be restricted to novel and unpublished work and will cover all important aspects of NO biology. The four-and-a-half day meeting will accommodate 850 participants and will- include 79 oral and up to 400 poster communications. Presentations will be selected on a competitive basis, by the consensus opinion of a panel of distinguished advisors, using the sole criterion of scientific merit. Therapeutic implications of the new biology of NO will be an important aspect of the meeting and will comprise 16 of the 79 allotted time slots for oral communications; these lie dominantly in the realm of vascular biology. Funds are requested for publicity, meeting administration and services and to provide scholarships to deserving scientists whose participation would otherwise be impossible.